Practice characteristics and performance of primary care practitioners

The authors examined organizational characteristics of 16 primary care group practices to determine their influence on quality or quality improvement.

The authors used a data base compiled during a randomized, controlled trial of quality assurance interventions consisting of measures of guideline-related performance for 630 practitioners. The authors distinguished performance under practitioners' control from performance determined partly by systems of care within each practice. The authors conducted analyses for all criteria (practitioner-controlled and system-dependent criteria) before and after quality assurance interventions using analysis of variance models with adjustments in performance scores for patient and practitioner characteristics. Specifically, the authors used as covariates the full-time versus part-time status of practitioners, whether practices were in hospitals or in health centers, and for practices within health centers, the effect of size of practice in terms of the average number of practitioners on staff during a time period.

Full-time practitioners performed similarly before interventions but improved more after interventions overall and for practitioner-controlled criteria than did part-time practitioners. Health center practitioners performed better than did those in hospitals for system-dependent criteria before intervention. For system-dependent criteria, larger health centers performed better before interventions and improved more than did smaller health centers.

Organizational characteristics including practice size and location (hospital-based or not) and full- or part-time status of practitioners should be considered in measuring quality and planning quality improvements, particularly in relation to care that is predominantly under system versus practitioner control.